1. Field of the Invention
The present invention relates generally to robots, and more particularly but not exclusively to robots employed in wafer processing systems.
2. Description of the Background Art
In semiconductor wafer processing systems, robots are employed to move wafers from one location to another. For example, a robot may be employed to pick up a wafer from a wafer cassette in a loading port, and move the wafer to a load lock. From the load lock, another robot or wafer transfer mechanism may move the wafer to a reactor where the wafer is processed, or to an intermediate location, such as a transfer chamber. Robots advantageously allow processing of wafers with minimum operator intervention.
To accurately place and pick up wafers, a robot needs to know the coordinates of various locations in the wafer processing system. Because of variations between wafer processing systems, coordinates are programmed into a robot after it is installed in a wafer processing system. Programming location coordinates into a robot, also referred to as “robot calibration”, is oftentimes done manually by a technician or a field service engineer. Thus, depending on the number of hand-off (i.e., pick and place) locations, calibrating a robot may take some time, and can be tedious and error-prone. In a production environment, replacing a failing robot with a new one consumes valuable production time because the new robot will have to be calibrated before the wafer processing system can be brought back up to process wafers.